U.S. patent application number 13/123125 was filed with the patent office on 2011-10-06 for device for variably adjusting the control times of gas exchange valves of an internal combustion engine.
This patent application is currently assigned to SCHAEFFLER TECHNOLOGIES GMBH & CO. KG. Invention is credited to Andreas Strauss.
Application Number | 20110239966 13/123125 |
Document ID | / |
Family ID | 41319702 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110239966 |
Kind Code |
A1 |
Strauss; Andreas |
October 6, 2011 |
DEVICE FOR VARIABLY ADJUSTING THE CONTROL TIMES OF GAS EXCHANGE
VALVES OF AN INTERNAL COMBUSTION ENGINE
Abstract
The invention relates to a device (11) for variably adjusting
the control times of gas exchange valves (9, 10) of an internal
combustion engine (1) having a hydraulic phase shifting device
(12), a camshaft (6, 7), and a pressure accumulator (15), wherein
the phase shifting device (12) can be brought into a drive
connection with a crankshaft (2) and is connected to the camshaft
(6, 7) in a rotationally fixed manner, wherein a phase position of
the camshaft (6, 7) relative to the crankshaft (2) can be variably
adjusted by means of the phase shifting device (12) and wherein the
interior of the camshaft (6, 7) comprises a cavity (38).
Inventors: |
Strauss; Andreas;
(Forchheim, DE) |
Assignee: |
SCHAEFFLER TECHNOLOGIES GMBH &
CO. KG
Herzogenaurach
DE
|
Family ID: |
41319702 |
Appl. No.: |
13/123125 |
Filed: |
September 9, 2009 |
PCT Filed: |
September 9, 2009 |
PCT NO: |
PCT/EP09/61674 |
371 Date: |
April 7, 2011 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F01L 2001/34446
20130101; F01L 1/3442 20130101; F01L 1/344 20130101; F01L 2001/0475
20130101 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 1/344 20060101
F01L001/344 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2008 |
DE |
10 2008 050 672.9 |
Claims
1-10. (canceled)
11. A device for variably adjusting control times of gas exchange
valves of an internal combustion engine having a crankshaft,
comprising: a hydraulic phase setting device; a camshaft; and a
pressure accumulator, the phase setting device being connectable
with the crankshaft by a drive connection, and said phase setting
device being fixedly connected to the camshaft so as to rotate with
the camshaft, a phase relation of the camshaft relative to the
crankshaft being variably adjustable by the phase setting device,
an interior of the camshaft having a cavity, wherein the pressure
accumulator is arranged in the cavity and communicates with the
phase setting device.
12. The device as claimed in claim 11, wherein the pressure
accumulator includes a longitudinally displaceable piston.
13. The device as claimed in claim 12, wherein the pressure
accumulator includes a spring element that loads the piston with a
force counter to a force of a pressure medium.
14. The device as claimed in claim 12, wherein the pressure
accumulator includes a housing arranged in the cavity, the piston
being guided in the housing so as to be longitudinally
displaceable.
15. The device as claimed in claim 14, wherein the housing includes
at least one stop for limiting travel of the piston at least in one
displacement direction of the piston.
16. The device as claimed in claim 14, wherein the pressure
accumulator is arranged in a stationary manner in the cavity
between the housing and a wall of the cavity by a nonpositive
connection.
17. The device as claimed in claim 14, wherein the housing has a
guide section and the piston has an outer circumferential face that
is adapted to an inner circumferential face of the guide
section.
18. The device as claimed in claim 17, wherein the guide section
extends over an entire length of the piston.
19. The device as claimed in claim 17, wherein the housing has a
region of increased diameter at both axial ends of the guide
section, outer circumferential faces of the increased diameter
regions being adapted to a wall of the cavity.
20. The device as claimed in claim 10, wherein the camshaft is
tubular.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a device for variably adjusting the
control times of gas exchange valves of an internal combustion
engine having a hydraulic phase setting device, a camshaft and a
pressure accumulator, it being possible for the phase setting
device to be brought into a drive connection with a crankshaft, and
said phase setting device being connected fixedly to the camshaft
so as to rotate with it, a phase relation of the camshaft relative
to the crankshaft being variably adjustable by means of the phase
setting device, and the interior of the camshaft having a
cavity.
BACKGROUND OF THE INVENTION
[0002] In modern internal combustion engines, devices are used for
variably adjusting the control times of gas exchange valves, in
order for it to be possible to variably configure the phase
relation between the crankshaft and the camshaft in a defined
angular range, between a maximum early position and a maximum late
position. The device usually comprises a camshaft and a hydraulic
phase setting device, by means of which a phase relation between
the crankshaft and the camshaft can be changed in a targeted manner
by way of feeding in or discharging pressure medium. For this
purpose, the phase setting device is integrated into a drive train,
via which torque is transmitted from the crankshaft to the
camshaft. Said drive train can be realized, for example, as a belt
drive, chain drive or drive train can be realized, for example, as
a belt drive, a chain drive or a gearwheel drive.
[0003] A device of this type is known, for example, from DE 195 29
277 A1. The device comprises a phase setting device and a camshaft.
The phase setting device has an output element which is arranged
such that it can be rotated with respect to a drive element. The
drive element is drive connected to the crankshaft. The output
element and the drive element delimit a pressure space which is
divided by means of an axially displaceable piston into two
pressure chambers which act counter to one another. The piston is
displaced within the pressure space by feeding in or discharging
pressure medium from the pressure chambers. The piston has a
helical toothing system which meshes with a helical toothing system
of the camshaft. A targeted rotation of the camshaft with respect
to the crankshaft can therefore be brought about by the axial
displacement of the piston.
[0004] Furthermore, the device has a pressure accumulator which is
arranged in a crankcase or a cylinder head of the internal
combustion engine. During the normal operation of the internal
combustion engine, the pressure accumulator is filled with pressure
medium, as a rule the engine oil, by a pressure medium pump. If the
system pressure which is delivered by the pressure medium pump
falls below a value which is required for the functionally reliable
operation of the device, the pressure accumulator is emptied into
the pressure medium circuit of the internal combustion engine.
Brief minimum pressure undershoots within the pressure medium
system can therefore be absorbed and/or the volumetric flow can be
increased.
[0005] A disadvantage of this embodiment is the great space
requirement of the pressure accumulator within the crankcase or the
cylinder head.
OBJECT OF THE INVENTION
[0006] The invention is based on the object of providing a device
for variably adjusting the control times of gas exchange valves of
an internal combustion engine, it being intended that the
installation space requirement of the device is reduced.
[0007] According to the invention, the object is achieved by virtue
of the fact that the pressure accumulator is arranged in the cavity
and communicates with the phase setting device.
[0008] The device has at least one hydraulic phase setting device,
one camshaft and one pressure accumulator. The phase setting device
comprises at least one drive element and one output element. In the
mounted state of the device, the drive element is drive connected
to the crankshaft via a flexible drive, for example a belt or chain
drive or a gearwheel drive. The output element is arranged such
that it can be pivoted relative to the drive element in an angular
range and is fastened fixedly to the camshaft so as to rotate with
it.
[0009] At least one pressure chamber is provided within the device,
by the pressure loading of which at least one pressure chamber the
output element can be pivoted relative to the drive element and
therefore the camshaft can be pivoted relative to the crankshaft.
One or a plurality of pairs of pressure chambers which act counter
to one another is/are advantageously provided.
[0010] The camshaft has a cavity. Said camshaft can be configured,
for example, as a hollow shaft. Embodiments are likewise
conceivable, in which the camshaft is configured as a tube, on the
outer circumferential face of which cams are fastened in a
nonpositive manner, a positive manner or with a material to
material fit. However, camshafts of solid configuration are
likewise also conceivable, in which a cavity is provided, for
example in the form of a blind bore. The pressure accumulator is
arranged in the cavity of the camshaft. The pressure accumulator
can be connected in a stationary manner to the camshaft, for
example in a positive manner, a nonpositive manner or with a
material to material fit.
[0011] Pressure medium can be fed to the interior of the camshaft,
for example via a camshaft bearing. The pressure medium passes
firstly to the hydraulic phase setting device; and secondly to the
pressure accumulator which is filled with pressure medium during
the normal operation of the internal combustion engine. At the
beginning of a phase adjustment, a defined quantity of pressure
medium is removed from the pressure medium system of the internal
combustion engine. As a consequence of this, the system pressure
drops to a lower level. The system pressure which is present before
the adjustment is not available in its full extent for the phase
adjustment. The adjusting speed of the phase adjustment and
therefore the performance of the entire internal combustion engine
drop. If the pressure accumulator is filled, this pressure drop is
absorbed by it, and the adjusting speed is held at a high level.
The installation space requirement of the internal combustion
engine is significantly reduced by the arrangement of the pressure
accumulator within the camshaft, an installation space which is
otherwise unused.
[0012] In one implementation of the invention, it is proposed that
the pressure accumulator has a longitudinally displaceable piston.
Furthermore, the pressure accumulator can have a spring element
which loads the piston with a force counter to the force of the
pressure medium. As an alternative, for example, gas cushions can
be provided as force accumulators. The pressure accumulator can be
configured, for example, as a piston accumulator, in particular as
a piston spring accumulator. This represents a very robust
solution.
[0013] There is provision in one development of the invention for
the pressure accumulator to have a housing which is arranged in the
cavity and in which the piston is guided such that it can be
displaced longitudinally. A wall of the cavity of the camshaft
therefore does not have to be machined further in a complicated
manner. The running face of the piston is provided by an inner
circumferential face of the housing. The housing can be realized,
for example, as a cylindrical or pot-shaped sheet metal part which
can be manufactured, for example, by a chipless shaping process,
for example by a deep drawing method. As a result, the weight and
the manufacturing costs of the housing are kept low. As a result of
the deep drawing method, the running face of the piston is
automatically manufactured with the necessary accuracy. Complicated
further machining steps are not necessary.
[0014] Furthermore, there can be provision for the pressure
accumulator to be arranged in a stationary manner in the cavity
between the housing and a wall of said cavity by means of a
nonpositive connection. As an alternative, material to material or
positive connections can also be provided, such as adhesive,
soldered or welded connections.
[0015] There can be provision in one implementation for the housing
to have a guide section and for the piston to have an outer
circumferential face which is adapted to an inner circumferential
face of the guide section. The piston is guided in an axially
movable manner on a guide face of the guide section. Here, the
length of the guide section corresponds to the stroke of the piston
within the pressure accumulator. The guide section can extend, for
example, over the entire length of the piston. There can be
provision in this embodiment for the nonpositive connection between
the housing and the wall of the cavity to be configured along the
entire length of the guide section, as a result of which the
connection is given a high stability. For this purpose, its outer
circumferential face is to be adapted to the wall of the cavity. As
an alternative, there can be provision, at both axial ends of the
guide section, for the housing to have a region of increased
diameter, the outer circumferential faces of which are adapted to
the wall of the cavity. There is therefore a nonpositive connection
only between the regions of increased diameter and the wall of the
cavity. As a result, a deformation of the guide face is avoided
during the mounting of the pressure accumulator in the cavity,
which could lead to jamming of the piston in the housing.
[0016] Furthermore, there can be provision for the housing to have
at least one stop for limiting the travel of the piston at least in
one displacement direction of the piston, advantageously in both.
Furthermore, there can be provision for the camshaft to be of
tubular configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Further features of the invention result from the following
description and from the drawings, in which exemplary embodiments
of the invention are shown in simplified form. In the drawings:
[0018] FIG. 1 shows an internal combustion engine in an only very
diagrammatic way,
[0019] FIG. 2 shows a longitudinal section through a first
embodiment according to the invention of a device for changing the
control times of gas exchange valves of an internal combustion
engine,
[0020] FIG. 3 shows a cross section through the phase setting
device from FIG. 2 along the line III-III, the central screw not
being shown,
[0021] FIGS. 4, 5 show the detail X from FIG. 2, and
[0022] FIG. 6 shows an illustration of a further embodiment
according to the invention of a device, analogously to FIG. 4.
DETAILED DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 outlines an internal combustion engine 1, a piston 3
which is seated on a crankshaft 2 in a cylinder 4 being indicated.
In the embodiment which is shown, the crankshaft 2 is connected via
in each case one flexible drive 5 to an inlet camshaft 6 and outlet
camshaft 7, it being possible for a first and a second device 11 to
ensure a relative rotation between the crankshaft 2 and the
camshafts 6, 7. Cams 8 of the camshafts 6, 7 actuate one or more
inlet gas exchange valves 9 and one or more outlet gas exchange
valves 10. There can likewise be provision for only one of the
camshafts 6, 7 to be equipped with a device 11, or for only one
camshaft 6, 7 to be provided which is provided with a device
11.
[0024] FIGS. 2 and 3 show a first embodiment of a device 11
according to the invention in longitudinal and cross section. The
device 11 has a phase setting device 12, a camshaft 6, 7 and a
pressure accumulator 15.
[0025] The phase setting device 12 comprises a drive element 14, an
output element 16 and two side covers 17, 18 which are arranged on
the axial side faces of the drive element 14. The output element 16
is configured in the form of an impeller wheel and has a
substantially cylindrically configured hub element 19, from the
outer cylindrical circumferential face of which five vanes 20
extend in the radial direction to the outside in the embodiment
which is shown.
[0026] Starting from an outer circumferential wall 21 of the drive
element 14, five projections 22 extend radially to the inside. In
the embodiment which is shown, the projections 22 and the vanes 20
are configured integrally with the circumferential wall 21 and the
hub element 19, respectively. The drive element 14 is arranged such
that it can be rotated with respect to the output element 16 by
means of radially inner circumferential walls of the projections 22
relative to said output element 16.
[0027] A chain sprocket 23 is formed on an outer circumferential
face of the drive element 14, via which chain sprocket 23 torque
can be transmitted from the crankshaft 2 to the drive element 14 by
means of a chain drive (not shown). The output element 16 is
connected fixedly to the camshaft 6, 7 so as to rotate with it. For
this purpose, in the embodiment which is shown, a central screw 13
reaches through a central opening 16a of the output element 16 and
engages into a threaded section 25 of the camshaft 6, 7. Here, a
shoulder of the central screw 13 bears against that side face of
the output element 16 which faces away from the camshaft 6, 7.
[0028] In each case one of the side covers 17, 18 is arranged on
one of the axial side faces of the drive element 14 and is fixed
firmly on the latter so as to rotate with it. For this purpose, an
axial opening 26 is provided in each projection 22. Furthermore, in
each case five openings are provided in the side covers 17, 18,
which openings are arranged in such a way that they are aligned
with the axial openings 26. In each ease one screw 27 reaches
through an opening of the second side cover 18, an axial opening 26
and an opening of the first side cover 17. Here, a threaded section
of the screw 27 engages into a threaded section which is formed in
the opening of the first side cover 17.
[0029] A pressure space 28 is formed within the device 11 between
in each case two projections 22 which are adjacent in the
circumferential direction. Each of the pressure spaces 28 is
delimited in the circumferential direction by substantially
radially extending bounding walls 29, which lie opposite one
another, of adjacent projections 22, in the axial direction by the
side covers 17, 18, radially to the inside by the hub element 19
and radially to the outside by the circumferential wall 21. A vane
20 protrudes into each of the pressure spaces 28, the vanes 20
being configured in such a way that they bear both against the side
covers 17, 18 and against the circumferential wall 21. Each vane 20
therefore divides the respective pressure space 28 into two
pressure chambers 30, 31 which act counter to one another.
[0030] The output element 16 is arranged such that it can be
rotated with respect to the drive element 14 in a defined angular
range. The angular range is delimited in one rotational direction
of the output element 16 by virtue of the fact that the vanes 20
come to bear against in each case one corresponding bounding wall
29 (early stop 32) of the pressure spaces 28. In an analogous
manner, the angular range in the other rotational direction is
delimited by virtue of the fact that the vanes 20 come to hear
against the other bounding walls 29 of the pressure spaces 28,
which bounding walls 29 act as late stop 33.
[0031] By loading one group of pressure chambers 30, 31 with
pressure and relieving the other group of pressure, the phase
relation of the drive element 14 with respect to the output element
16 (and therefore the phase relation of the camshaft 6, 7 with
respect to the crankshaft 2) can be varied. The phase relation can
be kept constant by loading both groups of pressure chambers 30, 31
with pressure.
[0032] In the region of a camshaft bearing 39, the camshaft 6, 7
has a plurality of openings 35, via which the pressure medium which
is delivered by a pressure medium pump 48 passes into the interior
of said camshaft 6, 7. A pressure medium path 36 which communicates
firstly with the openings 35 and secondly with the control valve 34
is formed within the camshaft 6, 7. A control valve 34 is arranged
in the interior of the central screw 13 in order to supply the
phase setting device 12 with pressure medium. By means of the
control valve 34, pressure medium can be guided optionally to the
first or second pressure chambers 30, 31 and can be discharged from
the respectively other pressure chambers 30, 31.
[0033] A pressure medium channel 37 which communicates firstly with
the pressure medium path 36 and secondly with a cavity 38 of the
camshaft 6, 7 of hollow configuration is provided in the interior
of the central screw 13. The pressure medium channel 37 is
configured as an axial hole which reaches through the threaded
section of the central screw 13.
[0034] The pressure accumulator 15 is arranged in the cavity 38.
FIGS. 4 and 5 show the pressure accumulator in the filled (FIG. 4)
and in the emptied state (FIG. 5). The pressure accumulator 15
comprises a housing 40, a piston 41 and a force accumulator, a
spring element 42 in the embodiment which is shown. The housing 40
is arranged within the cavity 38 and is connected fixedly to a wall
43 of the cavity 38. In the embodiment which is shown, the outer
circumferential face of the housing 40 is adapted to the wall 43
and is connected nonpositively to the latter. Embodiments are also
conceivable, in which the housing 40 is connected to the wall 43
with a material to material fit or in a positive manner. In
addition, the housing 40 can be fixed by means of a securing ring
24.
[0035] The piston 41 is arranged in the interior of the housing 40
such that it can be displaced axially, said piston 41 being of
cup-shaped configuration in the embodiment which is shown. The
entire housing 40 serves as guide section 44, an inner
circumferential face of the guide section 44 being configured as
guide face 45 for a cylindrical section of the piston 41. Here, the
cylindrical section of the piston 41 can bear entirely or in
regions against the guide face 45. The outer circumferential face
of the piston 41 is adapted to the guide face 45 in such a way that
it divides the housing 40 into two regions axially in front of and
behind the head of the piston 41 in a manner which is sealed with
respect to pressure medium. The piston 41 is loaded with a force by
means of the spring element 42 which is arranged in the region of
the cylindrical section. The spring element 42 is supported on one
side on a stop 46 which is formed at that end of the housing 40
which faces away from the phase setting device 12, and on the other
side on the head of the piston 41. The spring element 42 therefore
loads the piston 41 with a force in the direction of the pressure
medium channel 37. Here, the displacement travel of the piston 41
in the direction of the pressure medium channel 37 is delimited by
a stop 46 which is formed at the end which faces the phase setting
device 12.
[0036] In the embodiment which is shown, the housing 40 and the
piston 41 are configured as sheet metal parts which are
manufactured, for example, by a chipless manufacturing method, for
example a deep drawing method. This has the advantage that the
guide face 45 and the cylindrical section of the piston 41 can be
manufactured so precisely by this shaping process that they do not
have to be machined further. Expensive further machining steps of
the wall 43 of the cavity 38 are also dispensed with as a result of
the use of the housing 40.
[0037] FIG. 6 shows a second embodiment of a pressure accumulator
15. This has the difference from the first embodiment that the
guide section 44 does not extend over the entire axial length of
the housing 41 and does not bear against the wall 43 of the cavity
38. The guide section 44 is adjoined in the axial direction by in
each case one region 47 of increased diameter. Here, the outer
circumferential faces of the regions 47 of increased diameter are
adapted to the wall 43. The nonpositive connection between the
housing 40 and the wall 43 therefore exists only in the area of the
regions 47 of increased diameter. As a result, a deformation of the
guide face 45 during the operation of pressing the housing 40 into
the cavity 38 is avoided.
[0038] During the operation of the internal combustion engine 1,
pressure medium is guided from the pressure medium pump 48 via the
openings 35, the pressure medium path 36 and the control valve 34
to the phase setting device 12. Furthermore, pressure medium is
guided via the openings 35, the pressure medium path 36, the
pressure medium channel 37 and a housing opening 50 into the
housing 40. The pressure medium loads the piston 41 with a force,
as a result of which said piston 41 is displaced axially counter to
the force of the spring element 42. The pressure accumulator 15 is
filled (FIG. 4). If the system pressure which is delivered by the
pressure medium pump 48 drops, the force of the pressure medium on
the piston 41 drops, as a result of which said piston 41 is
displaced by the spring element 42 in the direction of the pressure
medium channel 37 and therefore feeds pressure medium to the
system. On account of a nonreturn valve 49, the pressure medium is
prevented from flowing back into the pressure medium system and is
therefore completely available to the phase setting device 12, as a
result of which its response sensitivity and its adjusting speed
are kept at a high level.
LIST OF DESIGNATIONS
[0039] 1 Internal combustion engine [0040] 2 Crankshaft [0041] 3
Piston [0042] 4 Cylinder [0043] 5 Flexible drive [0044] 6 Inlet
camshaft [0045] 7 Outlet camshaft [0046] 8 Cam [0047] 9 Inlet gas
exchange valve [0048] 10 Outlet gas exchange valve [0049] 11 Device
[0050] 12 Phase setting device [0051] 13 Central screw [0052] 14
Drive element [0053] 15 Pressure accumulator [0054] 16 Output
element [0055] 16a Central opening [0056] 17 Side cover [0057] 18
Side cover [0058] 19 Huh element [0059] 20 Vane [0060] 21
Circumferential wall [0061] 22 Projection [0062] 23 Chain sprocket
[0063] 24 Securing ring [0064] 25 Threaded section [0065] 26 Axial
opening [0066] 27 Screw [0067] 28 Pressure space [0068] 29 Bounding
wall [0069] 30 First pressure chamber [0070] 31 Second pressure
chamber [0071] 32 Early stop [0072] 33 Late stop [0073] 34 Control
valve [0074] 35 Openings [0075] 36 Pressure medium path [0076] 37
Pressure medium channel [0077] 38 Cavity [0078] 39 Camshaft bearing
[0079] 40 Housing [0080] 41 Piston [0081] 42 Spring element [0082]
43 Wall [0083] 44 Guide section [0084] 45 Guide face [0085] 46 Stop
[0086] 47 Region [0087] 48 Pressure medium pump [0088] 49 Nonreturn
valve [0089] 50 Housing opening
* * * * *